Fiber chopper and method of chopping

ABSTRACT

A method and apparatus for separating long, unwound items like fiber, fiber strands, yarn, etc. into short lengths. The apparatus has a backup roll, a blade roll, an idler roll, and a new-strand starting mechanism. The improvements include a guide roll for the items spaced from and located upstream of the apparatus and a movable, two-part idler roll on the apparatus for increasing the width of a separating portion of the backup roll.

BACKGROUND

The present invention involves an improved chopper for choppingcontinuous or very long loose items such as fiber, fiber strands, yarn,wire, string, ribbon, tape and the like by pulling the item(s) into thechopper while the loose items are held tightly against the surface of arotating backup roll and carrying the item(s) on into a nip between arotating blade roll and the rotating backup roll where they areseparated into short pieces. More specifically the present inventioninvolves a chopper having improved mechanisms and features.

It has long been known to chop continuous fibers or fiber strands intoshort lengths of about 3 inches or shorter. Billions of pounds of suchproduct including chopped glass fibers and fiber strands are producedeach year in process and chopping apparatus such as disclosed in U.S.Pat. Nos. 5,970,837, 4,551,160, 4,398,934, 3,508,461, and 3,869,268, thedisclosures of which are incorporated herein by reference. The choppersdisclosed in these patents comprise a blade roll containing a pluralityof spaced apart blades for separating the fibers into short lengths, abackup roll, often or preferably driven, which the blades work againstto effect the separation and which pulls the fibers or fiber strands andin some cases, an idler roll to hold the fibers or fiber strands downonto the surface of the backup roll. In the chopped fiber processesdisclosed in these patents, the chopper is often the item most limitingthe productivity of the processes. These processes typically operatecontinuously every day of the year, 24 hours each day, except forfurnace rebuilds every 5-10 years.

The above choppers must be serviced every few hours, shifts or days,depending on the type of material being chopped, to replace a wornbackup roll, a blade roll, or both and sometimes other components of thechopper. These service shutdowns of the chopper often mean that all ofthe bushings being served by the chopper are not only disrupted, but donot produce any salable product until the chopper is again running andthe strands from each of the bushings have been restarted into thechopper. It usually takes 10-15 or more minutes to stop and service thechopper and to restart all of the 5-14 bushings that are normally servedby the chopper. The fiberizing bushings usually do not run well for thefirst hour or two after a chopper service shutdown because the bushingsloose their temperature equilibrium and uniformity during the disruptionand it takes a period of time to regain the desired equilibrium. Duringthis time the productivity is also reduced and the manual labor demandis increased.

Any improvement in the chopper that would allow the chopper to pull andchop faster and/or for longer times between service shutdowns, and/or topull and chop more fibers or fiber strands at a time would have anextremely positive impact on productivity and production costs. Theinvention comprises improvements to the type of chopper shown in U.S.Pat. No. 4,551,160. Problems exist with this type of chopper that causeinterruptions in production limiting productivity and causing higherthan necessary manufacturing costs. Some of these problems are strandbreakage in the chopper prior to chopping and resulting roll wraps. Eachrunning strand, due to the high speed it is being pulled and the natureof the strand, is subject to being broken by interference from the looseend of a broken strand, fuzz clumps comprised of a web of chopped orbroken fibers, and the worn, rough surface of the backup roll. When astrand breaks, the productivity of the fiberizing bushing is lost for afew minutes until the bushing beads down and the resulting new fiberstrand is started back into the chopper. Also, too frequently, when astrand breaks at the chopper, an idler roll wrap or a strand guide rollwrap resulting in or requiring most or all of the strands to be brokenout, the wrapped roll cleared of the wrapped strand or strands, and eachof the fiber strands from each of the fiberizing bushings laced backinto the chopper. Typical production time lost for the entire bushingleg from a roll wrap is about ten minutes.

SUMMARY OF THE INVENTION

The present invention is an improved chopper for separating long lengthsof one or more unwound items selected from a group consisting of fibers,fiber strands, wires, strings, tape(s), strip(s) and ribbon(s) intoshort lengths. One or more of, preferably a plurality of, the longlengths of material are pulled into the chopper in an unwound form atspeeds exceeding 1,000 FPM, preferably at speeds exceeding 2000 FPM,first by passing over an idler roll, a starting roll on a starting armand on into a nip of opposed peripheral surfaces of a pair of pullrolls, and subsequently by a moving elastomer layer on a peripheralworking surface of a rotating backup roll. The latter carries theitem(s) on into a nip between the elastomer working layer and blades ofa rotating blade roll. Both the blade roll and the backup roll areoutboard of a front of a cabinet that contains the conventional driveand roll biasing members. The improvement comprises any one or anycombination of; (A) a strand guide, preferably oscillating, for therunning strands that is located upstream of the chopper, (B) a newimproved, movable two part idler roll for avoiding roll wraps andincreasing the chopping width on the backup roll, and (C) a shieldlocated between the backup roll and the strand guide to protect thestrand guide from stray flying separated item(s). Preferably at leasttwo of the improved features are used and most preferably all threeimprovements are used on the chopper.

The invention also includes a method of chopping items as describedabove using the improved chopper described above having one or both ofthe improvements described above to separate the items into shortlengths while optimizing backup roll working layer life and blade livesand increasing chopping speed and productivity.

When the word “about” is used herein it is meant that the amount orcondition it modifies can vary some beyond that so long as theadvantages of the invention are realized. Practically, there is rarelythe time or resources available to very precisely determine the limitsof all the parameters of one's invention because to do so would requirean effort far greater than can be justified at the time the invention isbeing developed to a commercial reality. The skilled artisan understandsthis and expects that the disclosed results of the invention mightextend, at least somewhat, beyond one or more of the limits disclosed.Later, having the benefit of the inventors disclosure and understandingthe inventive concept and embodiments disclosed including the best modeknown to the inventor, the inventor and others can, without inventiveeffort, explore beyond the limits disclosed to determine if theinvention is realized beyond those limits and, when embodiments arefound to be without unexpected characteristics, those embodiments arewithin the meaning of the term about as used herein. It is not difficultfor the skilled artisan or others to determine whether such anembodiment is either as might be expected or, because of either a breakin the continuity of results or one or more features that aresignificantly better than reported by the inventor, is surprising andthus an unobvious teaching leading to a further advance in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational perspective view of a portion of a prior artchopper.

FIG. 2 is an elevation view of a portion of the chopper showing theseveral improvements of the invention described herein.

FIG. 3 is an elevation view of an idler roll in a starting position anda portion of the mount for moving the idler roll according to thepresent invention with a portion of one part of the idler roll cut awayto show its relation to another part of the idler roll.

FIG. 4 is an elevation view of the idler roll in a running position anda portion of the mount for moving the idler roll according to thepresent invention with a portion of one part of the idler roll cut awayto show its relation to another part of the idler roll.

FIG. 5 is a partial side view of the chopper shown in FIG. 2 showing theposition of a feature of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a front elevation perspective view of a portion of a priorart chopper 2, of the type shown in U.S. Pat. No. 4,551,160, and that isused in making chopped strand glass fiber. It comprises a cabinet front3, a blade roll 4 with spaced apart blades 5 contained in slots andprojecting from the periphery of an integrated hub 6, a backup roll 8and a free-wheeling idler roll 9. The blade roll 6 is usually madeentirely of metal, but can be made using a thermoplastic material tohold spaced apart blades such as the blade rolls shown in U.S. Pat. Nos.4,083,279, 4,249,441 and 4,287,799, the disclosures of which are hereinincorporated by reference.

The backup roll 8 is held on a spindle (not shown) with a hub 9 and alsohas a metal rim 11 on which is a notch and projection 12 for starting anew strand 7 of fibers into the chopper. The backup roll 8 is biasedagainst the blade roll 4 until the blades 5 press into the working layerof the backup roll 8 a proper amount forming a nip 14 to break orseparate fiber strands 1 into an array of short length or choppedstrands 15.

One or more, usually five or more and up to 14 or more strands 1, suchas glass fiber strands, each strand containing 400-6000 or more fibersand usually having water and/or an aqueous chemical sizing on theirsurfaces, are pulled by the backup roll 8 into the chopper 2 and the nip14. The strands 1 first run under a grooved guide roll 16, preferablywith one or two strands 1 in each groove, and upward and over a workingsurface 13 of the backup roll 8, i.e. the exposed peripheral surface ofthe backup roll 8 on which the running strands 1 lay against and aresupported while being severed by blades 5 on the blade roll 4. Theworking surface of the back up roll 8 is typically wider than theoscillating path of the glass fiber strands 1. The strands 1 then passunder the outer surface of the free-wheeling idler roll 9, which islocated to provide sufficient contact of the strands 1 on the surface ofthe backup roll 8 to enable the latter to pull the glass fiber strands1.

When a new strand 18 is ready to be started into the prior art chopperit is pulled to the front of the chopper 2 by the operator and pulledunder the separator roll 16 and the idler roll 9 and up over a fixed,preferably non-freewheeling starter roll 19 attached to the end of apivoting arm 20 and down between a nip of a pair of driven pull rolls,part of a conventional pull roll assembly 21, that pull the new strand18 at a first low speed and deliver the new strand into a conventionalscrap processing system, scrap bin or scrap basement. After the newstrand 18 is being pulled by the pull roll assembly 21 at a low initialspeed, the pull rolls 21, the pulling speed of the pull rolls 21 isramped up to bring the new strand 18 to at least close to the speed ofthe strands 1 running into the chopper 2. When that speed is reached,the pivot arm 20 is pivoted counterclockwise to start the new strand 18into the chopper 2 in the manner disclosed in U.S. Pat. No. 4,551,160.

The improvements to the chopper, according to the present invention, areshown in FIG. 2 and in more detail in other figures described below. Thechopper 22 comprises a frame 32, a front wall 39 and in front of thefront wall are a backup roll 23 having a working surface 41, a bladeroll 24 with a plurality of spaced apart blades 45, moved to a positionto discharge the chopped strands 7 in a generally diagonal direction, anidler roll 25, a starter arm 20 and a starter roll 19.

The first improvement, designated A in FIG. 2, comprises an improvedfree-wheeling idler roll 25 and a moving mount, the former being in adifferent location, to produce superior results to prior art idlerrolls. The idler roll 9 shown in the chopper disclosed in U.S. Pat. No.4,551,160, has a constant diameter and this idler roll 9 is locatedbelow the backup roll 8 at a position of about 5 or 5:30 o'clock off ofthe backup roll 8. The idler roll 25 of the present invention issubstantially different in construction and action, and preferably isalso in substantially different location, than the prior art idler roll9. The improved idler roll 25 and mount 37 of the present invention isshown in FIGS. 3 and 4. FIG. 3 shows the idler roll 25 in a positionwhen operating with running strands 1 and a new strand 18 just beingstarted into the chopper 22. The improved idler roll 25 has two sectionsfor strand contact, a first section 50 having a first diameter andhaving a similar shape of the prior art idler roll 9, but comprised ofdifferent construction, and a second section 52 that is adjacent to andoverlaps the end of the first section 51. The second section 52 has thesame axis as the first section 50, but a second, larger, diameter. Bothsections of the idler roll 50,52 have a common fixed axle 51 that doesnot rotate. Both the first section 51 and the second section 52 aremounted to the axle 51 with conventional bearings allowing both to befree-wheeling, both sections being rotated by contact with either therunning strands 1 or a new strand 18.

The axle 51 is held by an arm 54 in a fixed, non-rotating manner. An endportion 55 of the arm 54 is attached in a fixed, non-rotating manner toa piston rod 56 of a fluid, gas or liquid powered, cylinder 58. Thehydraulic cylinder 58 is mounted behind the front wall 39 of the chopper22 on a member 59 of the chopper frame 32. The piston rod 56 issupported by the hydraulic cylinder 58 and by a bushing 57 slideablysurrounding the piston rod 56 and mounted in a hole (not shown) in thefront wall 39 in a conventional manner. The hydraulic cylinder 58 can beoperated with compressed air or other hydraulic fluid at elevatedpressure in the normal manner. The hydraulic cylinder can also bereplaced by various mechanical means, as one skilled in the art willrecognize after reading this disclosure, that will move the idler roll25 in the same or similar manner shown in FIGS. 3 and 4. A movable rod60 attached to a rotatable shaft 61 is in a vertical position to holdthe new-strand 18 in the desired location on the second section 52 ofthe movable idler roll 25. At the appropriate time, when ready to movethe strand onto the working layer 41, the shaft 61 is rotated to movethe rod 60 out of contact with the new-strand 18 allowing the new-strand18 to move onto the first section 50 to become one of the runningstrands 1.

FIG. 3 shows the position of the idler roll 25 when a new strand 18 ison the second section 52 very soon after lacing the new strand into thepull rolls 21. As soon as the new strand 18 has been accelerated to atleast near the speed of the running strands 1, a rod 60, preferablybrass and mounted on a rotatable shaft 61 extending out of the frontwall 3, holding the new strand onto the second section 52 is withdrawn,preferably by rotating shaft 61 clockwise sufficiently to clear the newstrand 18, allowing the new strand to move off of the second section 52and onto the first section 50 to join the running strands. This occursas the new strand 18 is being transferred to the working surface of thebackup roll 23 as will be seen later.

Once the new strand 18 has moved to the first section 50, the hydrauliccylinder 58 is energized to move the idler roll 25 to the position shownin FIG. 4, the running position. Without this movement of the idler roll25 between a running and starting position, much less, about 25 percentless, than the entire width of the working surface of the backup roll 23can be used for chopping the running strands, but by moving the idlerroll 25 to start a new strand on the new section 52, a substantiallywider portion of the working surface of the backup roll 23 can be used,increasing the life of the backup roll 23 significantly. In prior artchoppers using an unmovable idler roll the width of the working surfaceof the backup roll used for chopping the running strands 1 was about11.4 cm, but when the movable idler roll 25 width of the working surfaceof the backup roll used to chop running strands 1 is increased to about15.2 cm. Also, the movable idler 25 shown in FIG. 3 providessubstantially improved success in starting new strands into the chopperwith substantially fewer aborted starts than the prior art system.

A clearance 53 between an inside diameter of the second section 52 andan outside diameter of the first section 50 is sufficient that when thefirst section 50 is being driven by running strands 1, its rapidrotation does not cause more than a very slow rotation of the secondsection 52 when no new strand 18 is on the second section 52. Theclearance 53 should be at least about 0.05 cm and preferably about 0.038cm. A smaller clearance can cause the second section 52 to rotate fastenough, due to friction with the rapid movement of air close to thesurface of the outer surface of the first section 50, to jerk the newstrand 18 when it comes into contact with the outer surface of thesecond section 52 to occasionally break out the new strand 18. Theindependence of the two sections 50,52 allows the first section 51 torotate to produce a different surface speed than that of the secondsection 52. The still or only very slow rotation of the second section52 produces superior performance in starting a new strand 18 because itdoes not jerk the slow moving new strand 18 when first contacting thesurface of the second section 52 during lacing in of the new strand 18.A preferred material for the idler 25 is 440C stainless steel with afinish of about 30 microinches and a Rockwell C scale hardness of about62.

The new strand 18 first runs, or moves, at a slower surface speed thanthe strands 1 are running, and then, after having been placed over thestarter roll 19 and put into the pull rolls 21, is then accelerated upto at least close to the running speed of the running strands 1 prior tobeing transferred to the backup roll 23 and nip 14.

Another improvement involves removing the prior art oscillating strandguide roll 16 from the chopper and positioning an oscillating strandguide roll 26 upstream of the chopper 22 as shown in FIG. 2. In thislocation, the oscillating strand guide roll 26 provides substantiallybetter performance by removing it from a “dirty” area of the chopper, i.e. an area occasionally bombarded by flying fuzz clumps and choppedfiber and chopped strands 7 that have first adhered to the surface ofthe backup roll 23 and then were thrown off in the wrong direction, andalso by flying water spray and chemical sizing spray from the backuproll 23. In many fiberizing operations the operator has to place eachstrand 1 in a particular groove in the strand guide roll and it is mucheasier, and safer, to do this upstream of the chopper than closer to therapidly spinning backup roll 23. The strand guide roll 26, thatoscillates the running strands, is adjustable vertically to optimize thestrand path and to minimize the strand tension on the running strands 1.

The next improvement, designated C, is a shield 38 attached to the frame32 or a side of the chopper 22 and located between the home position ofthe start up roll 19 and the strand guide 26 to prevent chopped strand7, etc. from being thrown from the backup roll 23 onto strands 1 runninginto the chopper and to protect the operator when he positions each newstrand 18, or repositions a running strand, on the strand guide 26, seeFIGS. 2 and 5.

Many variations of the above improvements will be obvious to those ofordinary skill in the art given the above disclosure and these obviousvariations and modifications are covered by the scope of the claimsbelow.

1-10. (canceled)
 11. A method of separating long lengths of unwounditem(s) selected from the group consisting of fibers, fiber strands,string, yarn, wire, tape and ribbon into short pieces comprising feedingone or more items in an unwound form into a chopper at a speed exceedingabout 1000 FPM comprising a frame, a cabinet front, an idler rolloutboard of the cabinet front, a rotatable backup roll outboard of thecabinet front, the backup roll having a peripheral working layer with aperipheral working surface, a rotatable blade roll outboard of thecabinet front, the blade roll having a plurality of blades spaced apartaround its periphery for contact with and penetration of said item(s)and into the peripheral working layer of the backup roll and a biasingsystem for biasing the blades of the blade roll and the backup rolltogether, the improvement comprising placing the item(s) on at least oneof, a guide roll for the item(s) spaced from and upstream of thechopper, and a movable two-part idler roll located on the chopperoutboard of the cabinet front.
 12. The method of claim 11 wherein theitem(s) are placed on the movable, two-part idler roll for avoiding rollwraps and increasing the chopping width on the backup roll.
 13. Themethod of claim 11 wherein the movable, two-part idler roll comprises anaxle, a free-wheeling first roll mounted on the axle with bearings and afree wheeling second roll also mounted on the axle with bearings, thesecond roll having a larger outside diameter than the first roll and anedge of the second roll extending past an outboard edge of the firstroll, the clearance between an inside surface of that part of the secondroll that extends past the outboard edge of the first roll and anoutside surface of the first roll being at least about 0.9 centimeter.14. The method of claim 12 wherein the movable, two-part idler rollcomprises an axle, a free-wheeling first roll mounted on the axle withbearings and a free wheeling second roll also mounted on the axle withbearings, the second roll having a larger outside diameter than thefirst roll and an edge of the second roll extending past an outboardedge of the first roll, the clearance between an inside surface of thatpart of the second roll that extends past the outboard edge of the firstroll and an outside surface of the first roll being at least about 0.05centimeter.
 15. The method of claim 11 wherein the chopper comprises amechanism for moving the movable, two-part idler roll in a directionthat keeps peripheral surfaces of both a first roll part and a secondroll part generally parallel with said working surface of the workinglayer of the backup roll from a first position to a second position, thesecond roll being aligned with a portion of the working surface in thefirst position and being outboard of said working surface in the secondposition.
 16. The method of claim 12 wherein the chopper comprises amechanism for moving the movable, two-part idler roll in a directionthat keeps peripheral surfaces of both a first roll part and a secondroll part generally parallel with said working surface of the workinglayer of the backup roll from a first position to a second position, thesecond roll being aligned with a portion of the working surface in thefirst position and being outboard of said working surface in the secondposition.
 17. The method of claim 13 wherein the chopper comprises amechanism for moving the movable, two-part idler roll in a directionthat keeps peripheral surfaces of both the first roll part and thesecond roll part generally parallel with said working surface of theworking layer of the backup roll from a first position to a secondposition, the second roll being aligned with a portion of said workingsurface in the first position and being outboard of said working surfacein the second position.
 18. The method of claim 14 wherein the choppercomprises a mechanism for moving the movable, two-part idler roll in adirection that keeps peripheral surfaces of both the first roll part andthe second roll part generally parallel with said working surface of theworking layer backup roll from a first position to a second position,the second roll being aligned with a portion of said working surface inthe first position and being outboard of said working surface in thesecond position.
 19. The method of claim 11 wherein the guide roll forall of the running item(s) is located upstream of the chopper and spacedfrom the chopper.
 20. The method of claim 19 wherein the roll guideoscillates back and forth generally parallel to the working surface ofthe working layer of the backup roll to move the running item(s) backand forth across the most of the width of said working layer.
 21. Themethod of claim 11 wherein the item is at least one strand comprised ofglass fibers.
 22. The method of claim 12 wherein the item is at leastone strand comprised of glass fibers.
 23. The method of claim 16 whereinthe item is at least one strand comprised of glass fibers. 24-26.(canceled)